[1] Scientists assume that the size and shape of their pectoral fins have the right dimensions to minimize transport cost.

ISAF prefers to use "requiem sharks" due to the difficulty in identifying individual species.

The oldest member of the family is Archaeogaleus lengadocensis from the Early Cretaceous (Valanginian) of France.

Their elongated, torpedo-shaped bodies make them quick and agile swimmers, so they can easily attack any prey.

Some species are continually active, while others are capable of resting motionless for extended periods on the bottom.

They have a range of food sources depending on location and species, including bony fish, squid, octopus, lobster, turtles, marine mammals, seabirds, other sharks and rays; smaller species tend to select a narrow range of prey, but some very large species, especially the tiger shark (Galeocerdo cuvier), are virtually omnivorous.

They tend to be most active at night time,[7] where their impressive eyesight can help them sneak up on unsuspecting prey.

Some of the species have been shown to give specialized displays when confronted by divers or other sharks, which may be indicative of aggressive or defensive threat.